title: The involvement of InMIR167 in the regulation of expression of its target gene InARF8, and their participation in the vegetative and generative development of Ipomoea nil plants.
abstract: The plant hormone auxin plays a critical role in regulating plant growth and development. Recent advances have been made that having improved our understanding of auxin response pathways, primarily by characterizing the genes encoding auxin response factors (ARFs) in Arabidopsis. In addition, the expression of some ARFs is regulated by microRNAs (miRNAs). In Arabidopsis thaliana, ARF6 and ARF8 are targeted by miR167, whereas ARF10, ARF16 and ARF17 are targeted by miR160. Nevertheless, little is known about any possible interactions between miRNAs and the auxin signaling pathway during plant development. In this study, we isolated the miR167 target gene InARF8 cDNA from the cotyledons of the short day plant (SDP) Ipomoea nil (named also Pharbitis nil). Additionally, the In-miR167 precursor was identified from the I. nil EST database and analyses of InARF8 mRNA, In-pre-miR167 and mature miR167 accumulation in the plant's vegetative and generative organs were performed. The identified cDNA of InARF8 contains a miR167 complementary sequence and shows significant similarity to ARF8 cDNAs of other plant species. The predicted amino acid sequence of InARF8 includes all of the characteristic domains for ARF family transcription factors (B3 DNA-binding domain, AUX/IAA-CTD and a glutamine-rich region). Quantitative RT-PCR reactions and in situ hybridization indicated that InARF8 was expressed primarily in the shoot apices, leaf primordia and hypocotyls of I. nil seedlings, as well as in flower pistils and petals. The InARF8 transcript level increased consistently during the entire period of pistil development, whereas in the stamens, the greatest transcriptional activity occurred only during the intensive elongation phase. Additionally, an expression analysis of both the precursor In-pre-miR167 molecules identified and mature miRNA was performed. We observed that, in most of the organs examined, the InARF8 expression pattern was opposite to that of MIR167, indicating that the gene's activity was regulated by mRNA cleavage. Our findings suggested that InARF8 and InMIR167 participated in the development of young tissues, especially the shoot apices and flower elements. The main function of MIR167 appears to be to regulate InARF8 organ localization.
authors.affiliation: Chair of Plant Physiology and Biotechnology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, 87-100 Torun, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, 4 Wilenska Street, 87-100 Torun, Poland. Electronic address: pnowa@umk.pl.
authors.forename: Paulina
authors.initials: P
authors.lastname: Glazińska
authors.affiliation: Chair of Plant Physiology and Biotechnology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, 87-100 Torun, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, 4 Wilenska Street, 87-100 Torun, Poland.
authors.forename: Waldemar
authors.initials: W
authors.lastname: Wojciechowski
authors.affiliation: Chair of Plant Physiology and Biotechnology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, 87-100 Torun, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, 4 Wilenska Street, 87-100 Torun, Poland.
authors.forename: Emilia
authors.initials: E
authors.lastname: Wilmowicz
authors.affiliation: Chair of Plant Physiology and Biotechnology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, 87-100 Torun, Poland; Centre for Modern Interdisciplinary Technologies, Nicolaus Copernicus University, 4 Wilenska Street, 87-100 Torun, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Zienkiewicz
authors.affiliation: Chair of Plant Physiology and Biotechnology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, 87-100 Torun, Poland.
authors.forename: Kamil
authors.initials: K
authors.lastname: Frankowski
authors.affiliation: Chair of Plant Physiology and Biotechnology, Faculty of Biology and Environment Protection, Nicolaus Copernicus University, 1 Lwowska Street, 87-100 Torun, Poland.
authors.forename: Jan
authors.initials: J
authors.lastname: Kopcewicz
mesh_terms: D018506:Gene Expression Regulation, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D049915:Ipomoea nil / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics
chemical_list: D007210:Indoleacetic Acids; D035683:MicroRNAs; D014157:Transcription Factors
keywords: Auxin; InAFR8; Ipomoea nil; MiR167; MicroRNA